Slashdot videos: Now with more Slashdot!

View

Discuss

Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).

this_boat_is_real writes "Somewhere off the coast of Chile a pioneering underwater robot named Abe lies in a watery grave today. The Autonomous Benthic Explorer was one of the first truly independent research submersibles, being both unmanned and un-tethered to its launching ship. While on its 222nd research dive on Friday all contact with the craft was lost, the Woods Hole Oceanographic Institution has announced."

all the movies form the fifties about giant sea monsters being released by earthquakes are true! We must prepare are selves by watching hours of scifi original movies!
Its also no coincidence, 222nd dive? that's 1/3 evil.

Actually, not all robot vehicles last like the Mars rovers. They are sensational robots. There are many robots that never return from their maiden voyage. ABE has done a lot of good. It will be good to know what did the robot in, but this is not a day to panic. I recently let go of my 21 year old Honda Accord. It had 222k miles on it. Closest it got to an earth quake was a fender bender. At least ABE has avoided the humiliation of being gutted and sold for parts or put on display in some museum where people

I wonder where all the people are who were complaining about us littering the moon's "ecosystem" when NASA crashed that rocket into it? Surely this is a hundred times worse because it's now garbage in an actual ecosystem.

Mary Elizabeth Mastrantonio sulked through almost every production she was ever in. Maybe one of the reasons she's only got 27 entries on her reel and everything since 2004 has been TV and hasn't been in a decent movie since 2000.

Be difficult talent long enough and word gets around. She was pretty hot as Carmen in Color of Money, that was just three years before The Abyss.

the shrapnel created by a glass sphere implosion at two tons per square inch was enough to shred armored steel antennas and hydrophones. what chance do you think a flimsy balloon would have you fucking ignorant idiot ?

The people that design these things are smart. Smarter than the average poster here in their field. If Joe Armchairengineer can think it up, I'm pretty damn confident that the engineers behind ABE thought of it too.

In fact, from the WHOI release, there's this nugget:

ABE was equipped with several independent systems to bring it back to the surface at the end of a dive or should a fault occur. The Melville remained in the vicinity to see if ABE had resurfaced, at first searching for ABE’s strobe lights in the darkness. Researchers tried to establish radio contact with ABE in the event it had surfaced, but attempts turned up nothing.

Wherever it got stuck things may change. The critter might pop up years from now. Some little current change, an earthquake, or a bump from a fish and it may well be back in action or maybe it'll get caught in a shrimp net.

Who needs an emergency ascent system. We can just have it navigate up if it loses contact. It would just add weight. We've built it perfectly, it won't fail.

Then again, we don't know the real cause of why it lost contact. Did it lose power? Did it get swallowed by a whale? Did it get hung up in some human debris and the antennas knocked off? Did it get hit by some random ship at sea?

Learn to ballast, idiot. It would be dependent on the strength of the pumps and ballast tanks. Look at the pic. There aren't any ballast mechanisms or even elevation control surfaces other than two vertical propellers. Think of ABE as an undersea helicopter(or autogyro [wikipedia.org] to be precise) rather than a submarine.

It's been a while since I worked with the WHOI folks so my memory is a bit hazy. But generally these underwater submersibles come with:

A descent weight, used to make the craft negatively buoyant for the initial descent, then dropped to leave it neutrally buoyant.

An ascent weight, dropped at the end of the mission to make the neutrally buoyant craft positively buoyant.

A bladder which can be pumped with oil from a reservoir tank to fine-tune buoyancy.

Air doesn't work because of the enormous pressure involved. A 3000 psi scuba tank could only inflate a balloon down to about 2000 meters. Below that, the water pressure is greater than that inside the tank, and opening the valve would result in water forcing the balloon into the tank, rather than air inflating the balloon. A 10000 psi high pressure tank would work at 5000 meters, but would only result in about a 30% increase in volume, meaning you'd need a very big tank to be able to raise the entire craft in a catastrophic failure. Furthermore, the air would expand as the craft rose, risking rupturing the balloon. That's why the buoyancy control uses an oil bladder - oil is relatively incompressible.

Dropping the ascent weight helps raise the craft at the end of a mission. But usually they're relatively lightweight so you can attach them manually. The 17-inch glass spheres [benthos.com] typically used to house equipment provides over 50 pounds of buoyancy. The failure of one of these spheres at a depth of 3000 meters (~4500 psi) would release (4500 psi) * 4/3 * pi * (8.5 inches)^3 = 1.3 MJ of energy. A stick of dynamite is about 2.1 MJ, so losing one sphere is pretty much guaranteed to cause all the other spheres to fail. If the remainder of the craft somehow survived all that energy release, the loss in buoyancy would overwhelm what buoyancy you'd get by dropping the ascent weight.

> Furthermore, the air would expand as the craft rose, risking rupturing the balloon.

This is why such a balloon would need a _valve_ or a hole at the bottom, to allow excess gas to escape. It's precisely the same reason that SCUBA and deep sea divers doing a "free ascent" need to exhale quite a lot on their way up, lest they try to hold the expanding gas in their lungs and do something really destructive to their delicate alveoli and even give themselves serious embolisms.

Great. Next time I am designing an autonomous intelligent agent for 400m dives, I will include a balloon for ballasting. No examples from SCUBA equipment are relevant at the depths involved. Even with industrial dives using special gas mixes (low N2 & O2, high helium) unenclosed divers don't go anywhere near this depth. The point remains that the pressures involved make air unusable. Oh, and valves are a great point of failure in a high pressure environment.

Oh, dear. I'm not saying a balloon is a great idea, I'm merely saying that rupturing the balloon is not such a big risk if you leave an escape route for excess gas, such as a hole at the bottom of the balloon. And any valve should be at the _bottom_ of the balloon, so catastrophic failures are not a big issue.

Nor am I saying that a typical gas container would address this issue: I was simply pointing out one _small_ issue that is not as bad as one might think from the earlier post.

This is why such a balloon would need a _valve_ or a hole at the bottom, to allow excess gas to escape. It's precisely the same reason that SCUBA and deep sea divers doing a "free ascent" need to exhale quite a lot on their way up, lest they try to hold the expanding gas in their lungs and do something really destructive to their delicate alveoli and even give themselves serious embolisms.

Right. I wasn't saying the balloon idea was impossible, just explaining why it's inferior to oil and static pressure s

Thanks for that great explanation. Do you think that this is the reason why military subs don't go deep, because otherwise they would have to use an unwieldy oil bladder based bouyancy control system? I assume that if they did use such a system, when they flooded the ballast tanks in a crash dive a lot of oil would have to be "dumped" overboard; expensive, not easily replenished and leaves a big oil slick that would reveal your location (as opposed to a lot of quickly dispersing bubbles like in the movies

More because it would be a huge engineering investment for absolutely no military value. Having your submarine wandering around the ocean floor is pretty useless. I think most modern subs have maximum normal operating depths of five hundred metres or so.

Thanks for that great explanation. Do you think that this is the reason why military subs don't go deep, because otherwise they would have to use an unwieldy oil bladder based bouyancy control system?

Pretty much any military sub able to operate for long times underwater is nuclear powered. With that as an energy source, you don't really need to worry about fine-tuning your buoyancy. You can just propel yourself up or down. These small research subs are battery-powered, so you don't want to waste energy

If you fill it with something less dense than water, (gasoline, for instance), then it saves a lot of stress on the materials. I'm sure that the art has advanced a bit since 1957, but failure is almost always still a possibility.

'
You know, I've been sitting on 100 tons of that stuff. No one will buy it. They keep insisting that if I have it, it can't be unobtainium. I just stuffed it in the back of warehouse 13, with all the other crap people won't buy. {sigh}

And it's first and last thought was: Hm, I feel an interesting sensation all over me, pressing on me from all sides at once. I think I'll call it.... pressure. I wonder if it will be friends with me...<CRACK>

From the WHOI press release: "ABE was equipped with several independent systems to bring it back to the surface at the end of a dive or should a fault occur. The Melville remained in the vicinity to see if ABE had resurfaced, at first searching for ABE’s strobe lights in the darkness. Researchers tried to establish radio contact with ABE in the event it had surfaced, but attempts turned up nothing."

Protip: the people that design these things can, and likely do, fit square pegs in round holes.

Suggesting "durrr, attach a balloon" is, in my not very humble opinion, insulting to the engineers behind these things.

And yet..., if those engineers are so smart, how come poor ABE is rusting at the bottom of the ocean with only some ugly fishes for company. I think next time they should throw in a balloon, just in case.

I wonder if it had any kind of watchdog controlled system to inflate a flotation device or anything? (If it did, it apparently didn't work) You'd think it would be a sensible feature to have on such an expensive and unique piece of equipment.

A heavy device needs a lot of lift and that translates into a large physical volume of gas at depth. Keep in mind that every 33 feet of depth is one additional atmosphere of pressure. 66 feet down you need three times as much gas to inflate a lift bag as you would

Use mineral oil to make it very slightly buoyant, so that if power fails it floats to the surface. Pretty much incompressible. If you fill the whole thing you don't need the hull to withstand significant pressure. If you want a faster ascent, also add a balloon that gets inflated from a canister of liquid CO2. Hold the valve closed with a solenoid actuator.
Rocket science is engineering, but not all engineering is rocket science.

Isn't this the episode where Gilligan finds a mysterious robot in the water and the professor tries to use it to communicate to the outside world, and the skipper hits Gilligan in the head with his hat?

After such an illustrious career shouldn't they use this as the basis of their next design only adding to it additional features that have been proven on more recent designs from other teams? I mean making all these one-off designs like all the underwater robots seem to be has to be the least efficient way to go from both a cash perspective as well as a getting science done perspective.

They don't make very many of them. They're often made with the best technology available at the time. They're usually made with a specific set of tasks in mind, then later modified. Abe was around 15 years old.

I was going to ask if they suspected that I had hacked the OS and made it meet me at sea so I could steal it ( as a joke ), and then
I realized that this would make a good drug smuggling bot and really with all seriousness, isn't it possible that foul play could be at work and I'm guessing the device is worth at least a couple bucks to somebody who wants to get under the radar, so to speak.
From TFA, it seems also that it could be asleep. Maybe it just overslept.

With the increasing capability of these things being able to explore more and more of the ocean's depths, they might be stumbling upon things certain people/governments don't want them too.

How 'bout the wreck of the Thresher (U.S. Nuclear powered submarine), or the Soviet nuclear sub that the Glomar Challenger tried to bring up (under cover as a geo-physics expedition run by Howard Hughes). I believe the Soviet sub had nuclear weapons on board (either as torpedos or missiles, maybe mines).

Just happened to finish reading a good book about the history of deep sea exploration "Eternal Darkness", by Robert Ballard. He has been involved in this field since the 1970's & was former director at Woods Hole.

Anyway, the US Navy hired these guys to find the Thresher, and they did. He also discovered the Titanic. Great book, highly recommended.

I didn't say that the powers that be would try to recover their plutonium, just that they would want to prevent some other party from picking it and other items of interest from the sea floor. Like (in the case of a sunken nuclear sub) fully intact nuclear warheads/missiles with guidance mechanisms, code books, various nuclear attack plans. I would think that these items could be of enormous strategic utility.

Well there are many sad to see it go but it did a lot of great research. WHOI has a few more autonomous underwater robots - check out whoi.edu. BTW since the design of ABE was shaped like the Enterprise from Star Trek it had a registration number of NCC-1701B on its side - WHOI engineers are Trekkies too. My company is a videography contractor for WHOI.

I couldn't help to notice the similarities in this robot's design to the Starship Enterprise. As I looked closer it appears that somebody else had the same thought - the serial number on the robot is "NCC-1701B"!

In 2003, I was on a small team using a similar WHOI system called REMUS to take surveys of ports and waterways, looking for mines. We had been training with the system, mainly in Southern California and when Iraq started up, they decided that they wanted to try the new technology there. We did, and it was successful. http://www.joetalbot.net/pages/030401-N-3783H-075A.htm [joetalbot.net]
In the course of our training, we managed to get the things stuck, beached and lost several times despite a system that would take it to